Its interesting to note that dark matter is actually in competition with MiHsC and either could be correct at this point or elements of both.

The interesting thing is that physicists have no explanation for hyperenergetic cosmic rays at this time, my own idea is that it could be something really strange like pairs of black holes with particles spinning around the event horizons and a sudden change in one causing the particle streams to collide yielding very high energy collisions.

There is also the anecdotal link between radioactive half life fluctuations in certain isotopes (54Mn and 36Cl mostly) that seems to have a causal link with the rotation of the interior of the Sun suggesting an as yet unknown particle is causing a dipole like shift in half life ie a drop followed by a rise or vice versa, also there is a random element at least in 36Cl
A massive axion which fluctuates into an interacting form when it passes through Earth's magnetic field lines in a similar way to neutrino flavor change is a possibility however it could be more exotic still such as dark matter domain walls causing local changes in the cosmological constant.